1. Field of the Invention
The present invention relates to flow detection devices and more particularly to a detector for providing a warning in the event of an exhalation valve line disconnect in a mechanical ventilator system.
2. Description of the Prior Art
Pressure monitors have long been used in the exhalation lines of mechanical ventilators and the art associated with such use is well-known. In some systems, delivery of air to the patient is largely controlled by the exhalation valve. Thus, closure of the exhalation valve allows breathing gas to flow to the patient, while opening of the exhalation valve allows the patient to exhale to atmosphere. In many systems, the exhalation valve is pressure actuated and therefore, is closed by pressurized gas from the ventilator or other source. It is important that a disconnection in the pressurizing line for the exhalation valve be promptly discovered and rectified. This is normally done by using a pressure detector in the pressurizing system. A disconnect occurring between the ventilator and the pressure detector is readily discovered by prior art monitor and warning systems because of the almost instantaneous pressure drop to the pressure detector. A disconnect occurring downstream of the pressure detector may be more difficult to sense because back pressures may develop which will maintain the pressure detector in the pressure sensing mode, thus, a disconnect occurring in this part of the ventilator may go unnoticed. Thus, some of these prior art pressure monitoring devices have served a somewhat narrow purpose and have met special needs as presented by specific problems but have not met nor solved the problem of a disconnect occurring downstream of the pressure detector as described. Some of these prior art devices have been described in the following listed patents that were brought to the attention of the applicant through a novelty search conducted in the U.S. Patent and Trademark office:
______________________________________ Patent No. Title Inventor ______________________________________ 859,147 "Automatic Alarm Device" Strodtbeck 3,595,228 "Flow Line Break Alarm Device" Simon 3,870,012 "Pressure Drop Alarm Device" Metivier 2,854,001 "Breathing Apparatus" Humblet 3,952,773 "Breathing Gas Supply Controller" Hahn 4,054,133 "Control for a Demand Cannula" Myers 2,376,348 "Resuscitator" Fox 2,408,136 "Resuscitator-Insufflator-Aspirator" Fox 2,547,458 "Resuscitator" Goodner 2,881,757 "Respirator Control Systems" Haverland 3,046,979 "Lung Ventilators and Control Andreasen Mechanism Therefor" 3,073,298 "Respiratory Device" Stanton 3,319,627 "Intermittent Positive Pressure Windsor Breathing Apparatus" 3,385,295 "Apparatus for use in Administering Beasley Intermittent Positive Pressure Breathing Therapy" 3,485,243 "Respirator with Improved Bird et al Exhalation Valve and Control Means" 3,542,020 "Fluid Flow Devices" Bushman 3,630,196 "Manual Positive Pressure Breathing Bird Device" 3,867,934 "Pressure Monitor for a Lung Ollivier Ventilator" 3,903,881 "Respirator System and Method" Weigl 3,915,164 "Ventilator" Bird 3,974,828 "Ventilator and Method" Bird 4,044,763 "Ventilator and Method" Bird 4,067,329 " Tube Disconnection Warning Winicki Device" ______________________________________
Many of these prior art devices have had defects which have made them inappropriate and possibly dangerous. In some cases, they have been unreliable, difficult to control and inaccurate and, therefore, the quest for an improved disconnect sensor has continued.
It would, therefore, be a great advantage to the art to provide flow sensing means, operable to sense the pressure change resulting from disconnect in the exhalation valve pressurizing system, especially when such disconnect occurs downstream from the system pressure monitor.
It would be a further great advantage to provide such sensing means in a form easily adaptable to existing systems.
A further significant advantage would be realized if such sensing means could be provided in a convenient and economical form with little chance for installation error.